"The Soviets did a study about the correlation between maximum Olympic lifts and assistance exercises. The first four lifts with “highest correlation” for helping on the competition platform were:

Power Clean
Power Snatch
Clean
Overhead Squat

An article on one of America’s lifting superstars once summarized his secret with this wonderful line: “through extensive work on the powerclean had laid the foundation for John Terpak’s versatile athletic success.”

The Russians noted in the 1970′s that, simply, “A lifter must do many power cleans and squats to succeed.”

I’m also convinced that power cleans are one of the “secrets” to gaining muscle weight."

Performing cleans is considered by many to be a great overall mass, and strength movement.

Performing cleans is considered to be a hard lift to learn so most people just write it off. It's too hard to teach so we'll just ignore it.

Benching has many benefits, but also has many issues that are not taken into account when performed as part of a program.

Most people bench with horrible form and don't really understand the movement, yet we just ignore this fact and keep saying, BENCH!

Seems like the attitude is, laying down and doing crappy work is preferred to getting up off your butt, and learning to do something right.